California's U.S. attorneys say they are going after for-profit marijuana sellers. Advocates of the sales say they are concerned about buyers with health needs.

Birotte said the new strategy was not triggered by any specific event but was inspired by a stream of complaints from California law enforcement officials. The crackdown announced Friday came after months of consultation between the U.S. attorneys and Justice Department officials in Washington. The prosecutors acknowledged that they are not getting more money or prosecutors.

Steve Cooley, the Los Angeles County district attorney, predicted that intense coordination with federal prosecutors would make a huge difference. "It's advancing in the right direction from our perspective," he said. In Los Angeles, Jane Usher, a special assistant city attorney, said her office intended to work closely with Birotte's. "We're gratified that they see what we see, which is what began as an opportunity to help seriously ill patients has evolved into storefront drug sales and trafficking," she said.

California's attorney general, Kamala Harris, declined to discuss the announcement. Her office is revising the medical marijuana guidelines that Jerry Brown issued in 2008 when he was attorney general. Those guidelines note that state law does not allow "collectives, cooperatives or individuals to profit from the sale or distribution of marijuana" and advises that storefront dispensaries "may be legal."

Medical marijuana advocates were also perplexed that a federal department reporting to Obama is launching a crackdown that promises to be more fearsome than any under former President Bush. They believe that Obama betrayed a commitment he made as a candidate who casually joked about smoking marijuana and has strayed from the issues he was elected to address.

"They're wasting money they don't have," Leno said. "This is not the issue of the day. This doesn't create jobs. This does not keep the security of the nation intact. It doesn't clean the environment."

Leno said he believed the Obama administration has missed an opportunity to end the 15 years of legal chaos that began in 1996 when California voters passed Proposition 215. "If anything, they should be demonstrating leadership in resolving the conflict between federal and state laws," he said. "Until we deal with that, we're going to be going around in circles here."